Maintenance, repair and exchange of the main bearing in a direct drive outer rotor single bearing wind turbine is a complicated task as the direct drive permanent magnet generator forms the drive train of a direct drive generator and the main bearing is installed upwind of the drive train. Until now this task has involved disassembling the generator from the bed frame of the wind turbine and performing the actual maintenance work at ground level. Besides the lowering and raising of the large and heavy generator parts, the disassembly and assembly of the generator is a cumbersome task due to the small tolerances on the relative positioning of the rotor and stator parts of the generator with respect to each other. Accordingly, a significant amount of time, equipment and energy is necessary to carry out such maintenance.
EP 2 148 090 B1 describes a wind power turbine in which the blade assembly can be locked with respect to the stator of the electric generator regardless of the angular position of the blade assembly with respect to the stator. More specifically, EP 2 148 090 B1 proposes to achieve the desired locking by tightening screws extending through inclined holes in the blade assembly such that they pressure engage annular grooves which are formed in the stator assembly.
There may be a need for a simple way of performing maintenance on the main bearing of a direct drive single bearing wind turbine.